Carter, who welcomed his little boy with wife Lauren last April, after the couple married in 2014, opened up to ET in February -- during the Backstreet Boys' "Larger Than Life" residency shows at Planet Hollywood in Las Vegas -- about how fatherhood has changed his life for the better

"He's just a bundle of joy and it melts my heart and gives me purpose and reason to keep on staying healthy, staying motivated and all of those things," Carter sweetly told ET. "He's a really good, solid thing for me to have in my life."